Door for a refrigerated merchandiser

ABSTRACT

A refrigerated merchandiser including a case defining a product display area and a door coupled to the case to provide access to the product display area. The door includes a glass panel assembly including a glass panel, and a conductive coating applied to the glass panel and defining a serpentine conductive path on the glass panel. The merchandiser also includes a power supply in electrical communication with the conductive coating to heat the glass panel along the serpentine conductive path.

BACKGROUND

The present invention relates to doors for refrigerated merchandisers and, more particularly, to a conductive coating applied to the doors.

Refrigerated merchandisers generally include a case defining a product display area for supporting and displaying food products to be visible and accessible through an opening in the front of the case. Refrigerated merchandisers are generally used in retail food store applications such as grocery or convenient stores or other locations where food product is displayed in a refrigerated condition. Some refrigerated merchandisers include doors to enclose the product display area of the case and reduce the amount of cold air released into the surrounding environment. The doors typically include a glass panel, allowing a consumer to view the food products stored inside the case.

Refrigerated merchandisers may be susceptible to condensation forming on the glass panel of the door, which obstructs viewing of the food product positioned inside the case. In particular, condensation is most likely to form at the coldest portion of the glass panel, which is typically near the bottom of the glass panel.

SUMMARY

In one construction, the invention provides a refrigerated merchandiser including a case that defines a product display area and a door that is coupled to the case to provide access to the product display area. The door includes a glass panel assembly including a glass panel, and a conductive coating applied to the glass panel and defining a serpentine conductive path on the glass panel. The merchandiser also includes a power supply in electrical communication with the conductive coating to heat the glass panel along the serpentine conductive path.

In another construction, the invention provides a door including a glass panel, and a conductive coating applied to the glass panel and defining a serpentine conductive path on the glass panel.

In yet another construction, the invention provides a door for a refrigerated merchandiser. The door includes a glass panel and a conductive coating that is applied to the glass panel. The conductive coating has a first gap defined in the coating along a periphery of the conductive coating, a second gap connected to and extending inward from the first gap disposed adjacent a first side of the glass panel toward a central area of the glass panel, and a third gap connected to and extending inward from the first gap disposed adjacent a second side of the glass panel toward a central area of the glass panel.

Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a refrigerated merchandiser including doors embodying the invention.

FIG. 2 is a perspective view of one door of the refrigerated merchandiser.

Before any constructions of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other constructions and of being practiced or of being carried out in various ways.

DETAILED DESCRIPTION

FIG. 1 illustrates one construction of a refrigerated merchandiser 10 that may be located in a supermarket or a convenience store or other retail setting (not shown) for presenting fresh food, beverages, and other food product (not shown) to consumers. The refrigerated merchandiser 10 includes a case 14 and a plurality of doors 18 that are coupled to the case 14. The illustrated case 14 has a base 19, a rear wall 20, and a canopy 21 that cooperatively define a product display area 22 supporting food product 26 (e.g., on shelves 30). The product display area 22 is accessible adjacent the front of the case 14 via the doors 18. Although the refrigerated merchandiser 10 includes four doors 18 providing access to the product display area 22, it will be appreciated that the refrigerated merchandiser 10 may include fewer or more than four doors 18.

The refrigerated merchandiser 10 also includes at least a portion of a refrigeration system (not shown) that provides a refrigerated airflow to the product display area 22 (e.g., via apertures in the rear wall 20, a discharge outlet in the canopy 21, etc.). The refrigeration system generally includes an evaporator that is located within an air passageway internal to the case and that is fluidly connected between a condenser (not shown) and one or more compressors. Such refrigeration system arrangements are well known in the art., and as such, these features will not be described in detail.

FIG. 2 illustrates one door 18 of the refrigerated merchandiser 10. The door 18 includes a frame 38 that surrounds the perimeter of a glass panel assembly 42, and a handle 46 to facilitate moving the door 18 between open and closed positions. A hinge 50 is positioned on one side of the frame 38 to couple the door 18 to the case 14 so that the door 18 can be pivoted about the hinge 50 to allow access to the interior of the case 14. The door 18 may instead be slidably engaged with a portion of the base 20 within a track to allow access to the food product 26. The glass panel assembly 42 permits viewing of the food product 26 from outside the case 16 and can include one or more glass panels 52 (e.g., formed of low emissivity glass) that are spaced apart from each other (e.g., by spacers).

As shown in FIG. 2, a transparent resistive or conductive coating (e.g., a metallic pyrolytic coating, a magnetic sputter vacuum deposition coating, etc.) is applied to a surface of a glass panel 52 to heat the door 18 to inhibit formation of fog and condensation on the glass panel assembly 42 (e.g., on an exterior glass panel 52, an interior glass panel 52, or both). The coating is electrically connected to a power supply 54 by foil strips or bus bars (not shown) that can be positioned between the frame 38 and the glass panel 52, although other power connections can be used. A protective layer or film can be applied over the coating to protect the coating from direct contact.

With reference to FIG. 2, portions of the coating are removed or etched (e.g., by laser deletion) along one or more lines 56 on the glass panel 52 to form one or more paths 58 of heat or conduction along a surface of the glass panel assembly 42. That is, non-conductive gaps (represented by etched lines 56) are formed in the coating to define one or more conductive paths along the glass panel 52 between the etched lines 56 so that different areas or sections of the glass panel 52 have different levels of conduction and therefore different levels of heat. The conductive path(s) are relatively narrow or small in areas of the glass panel 52 (e.g., the central and bottom areas of the glass panel 52) that are colder (i.e. highly susceptible to fogging and condensation), whereas the conductive path(s) are relatively wide or large in areas of the glass panel 52 (e.g., the upper area of the glass panel 52) that are naturally warmer (i.e. less susceptible to fogging and condensation). As will be appreciated by one of ordinary skill in the art, the narrow areas have a relatively high watt density and the wide areas have a relatively low watt density.

The illustrated coating is etched on the glass panel 52 to define a labrynthian or serpentine conductive path 58 (illustrated by arrows in FIG. 2) on the glass panel 52 along which current flows. As shown in FIG. 2, an outer peripheral gap 56 a is etched in the coating adjacent the frame 38 to define a conductive boundary on the glass panel 52. In addition, several gaps 56 b, 56 c branch from the outer peripheral gap 56 a so that the gaps 56 a-c, when taken as a whole, define a conductive pattern or profile on the glass panel 52 that focuses heat energy in one or more areas of the glass panel assembly 42 that need to be cleared of fog or condensation.

With reference to the orientation of the door 18 illustrated in FIG. 2, the branch gaps 56 b extend inward from a left side segment 62 of the outer peripheral gap 56 a laterally across a substantial portion of the width of the glass panel 52. As illustrated, the three lowermost branch gaps 56 b extend horizontally across the glass panel 52 from adjacent the left side of the glass panel 52 and terminate or stop short of the right side of the glass panel 52 and a right side segment 66 of the outer peripheral gap 56. The uppermost branch gap 56 b extends generally downward and across the glass panel 52 at an angle 64 relative to the left side of the glass panel 52, and terminates in a central area of the glass panel 52.

The branch gap 56 c has a first gap segment 70 that extends inward from the left side segment 62 of the outer peripheral gap 56 a (as viewed in FIG. 2) laterally across a substantial portion of the width of the glass panel 52 below the lowermost branch gap 56 b. The branch gap 56 c also has a second gap segment 74 that extends upward (generally vertically) between the terminated or free ends of the branch gaps 56 b and the right side segment 66 of the outer peripheral gap 56 a. That is, the illustrated second gap segment 74 extends through (e.g., bisects) the area of the coating between the terminated ends of the branch gaps 56 b and the right side segment 66 of the peripheral gap 56 a. A lower portion of the second gap segment 74 extends generally parallel to the right side segment 66 and, at a location approximately midway up the glass panel 52, the second gap segment 74 extends upward and inward from the right side segment 66 at a non-zero angle 76 relative to the right side segment 66 (i.e. at an angle relative to a horizontal axis and a vertical axis). The second gap segment 74 terminates below a top of the glass panel 52 (i.e. the illustrated second gap segment 74 terminates in an upper central area of the glass panel 52) and does not intersect the peripheral gap 56 a.

A plurality of third gap segments 78 extends horizontally from the second gap segment 74 toward the left side of the glass panel 52. As illustrated, the two lowermost third gap segments 78 extend horizontally between the three lowermost branch gaps 56 b and pass through (e.g., bisect) the coating in the area between the branch gaps 56 b. The uppermost third gap segment 78 extends horizontally laterally across the glass panel 52 above the three lowermost branch gaps 56 b, and further extends at a non-zero angle relative to horizontal and vertical axes toward the left side segment 62 of the peripheral gap 56 a. Each of the third gap segments 78 terminates at a location that is short of (i.e. does not intersect) the left side segment 62. Generally, the terminated ends of the branch gaps 56 b and the branch gap 56 c define free ends of the branch gaps 56 b, 56 c that do not intersect another etched gap. In this way, the conductive path 58 is defined between adjacent gaps 56 a-c.

As illustrated, the path 58 extends horizontally from the power supply 54 along a bottom of the glass panel 52 between the peripheral gap 56 a and the first gap segment 70 of the branch gap 56 c. The path further extends generally vertically along the right side of the glass panel 52 between the peripheral gap 56 a and the second gap segment 74 of the branch gap 56 c. In this area, the conductive path 58 continuously widens from the point at which the second gap segment 74 is angled away from the right side segment 66. The conductive path 58 also wraps around the end of the second gap segment 74 and extends substantially vertically between the uppermost branch gap 56 b and the second gap segment 74. The path 58 further wraps around the free end of the uppermost branch gap 56 b and extends substantially horizontally across the glass panel 52 before wrapping around the free end of the uppermost third gap segment. The path 58 further zigzags between the three lowermost branch gaps 56 b and the third gap segments back to the power supply 54.

While the illustrated conductive path 58 is shown as proceeding from the power supply 54 along the bottom and right-side portions of the glass panel 52, and then through the zigzag section before returning to the power supply, it should be understood that the path 58 can be reversed. Also, it will be appreciated that gaps can be etched into the coating in any suitable orientation and arrangement to define other serpentine profiles for the conductive path 58 (e.g., a substantially vertically-oriented conductive path, etc.) while still providing a high watt density in desired areas of the glass panel assembly 42. Furthermore, the conductive path 58 can be defined by substantially uniformly arranged gaps, or randomly arranged gaps, or any combination of uniformly and randomly arranged gaps.

With continued reference to FIG. 2, the illustrated conductive path 58 is relatively narrow between the peripheral gap 56 a, the first gap segment 70, and the lower portion of the second gap segment 74, and between the three lowermost branch gaps 56 b, the third gap segments 78, the first gap segment 70, and the lower portion of the second gap segment 74. On the other hand, the conductive path is relatively wide alongside the uppermost branch gap 56 b and the uppermost portion of the second gap segment 74, with a narrower neck or section 82 between the free end of the uppermost branch gap 56 b and the adjacent portion of the second gap segment 74. Stated another way, the three lowermost gaps 56 b, the gap segments 70, 74, 78, and the section 82 disposed in the central and lower areas of the glass panel assembly 42 are spaced in close proximity to each other so that the heat density is relatively high to inhibit or quickly remove fog or condensation from these areas, whereas the uppermost gap 56 b, and the gap segments 74, 78 disposed in the upper area the glass panel assembly 42 are spaced relatively far apart from each other so that the heat density is relatively low. Because the glass panel assembly 42 is more susceptible to fog and condensation adjacent the central and lower areas, concentrating the heat density in these areas will quickly remove any fog or condensation that may form as compared to conventional glass panel coatings.

As illustrated, the coating is applied to the entire surface of the glass panel 52, and laser deletion or other suitable techniques (e.g., by omitting sections of coating on the glass panel 52) are utilized to remove or etch the gaps 56 a-c. The serpentine conductive path 58 has areas of high resistance (and thus a high watt density) and areas of low resistance (and thus a low watt density) that cooperatively define a path of conductivity (or resistance) that is longer than the width or length of the glass panel 52 and that is longer than the distance separating the positive and negative bus bars 54 a, 54 b. As such, less busbar material is needed to conduct current to the top and bottom of the glass panel 52.

The serpentine nature of the conductive path 58 also enables the use a conductive coating that has an increased thickness and a low value of emissivity (E<0.026), which results in a higher conductivity (i.e. lower resistance) while avoiding an increase in wattage needed to heat the door 18. The equation for wattage is known to be:

$W = \frac{V_{input}^{2}*144}{V_{Resistance}*D^{2}}$

For example, by applying a standard 120V power supply (V_(Input)) to a conductive coating that has a resistance of 3 ohms per square inch (V_(Resistance)), and a serpentine conductive path 58 that has an overall distance of approximately 310 inches (D), only an average of approximately 7 Watts per square foot are needed to clear fog and condensation from the door 18. The wattage is slightly higher in the narrower sections of the path 58 and is slightly lower in the wider sections. By arranging the narrower sections in the area of the glass panel 52 where fog and condensation is most likely to occur, any fog or condensation that forms can be quickly removed without using much power. While not shown, a controller and a sensor (e.g., temperature) can be used to control when power is applied to the conductive coating to prevent or remove fog or condensation. Also, some or all of the doors 18 on the merchandiser 10 can be electrically connected to a common power supply so that a clearing interval can be initiated simultaneously on the doors 18.

Various features and advantages of the invention are set forth in the following claims. 

What is claimed is:
 1. A refrigerated merchandiser comprising: a case defining a product display area; a door coupled to the case to provide access to the product display area, the door including: a glass panel assembly including a glass panel; a conductive coating applied to the glass panel and defining a serpentine conductive path on the glass panel; and a power supply in electrical communication with the conductive coating to heat the glass panel along the serpentine conductive path.
 2. The merchandiser of claim 1, further comprising a plurality of gaps formed in the coating and defining the serpentine conductive path between adjacent gaps, and wherein a distance between adjacent gaps on the glass panel varies along the glass panel to vary the amount of heat applied to different areas of the glass panel.
 3. The merchandiser of claim 2, wherein the gaps extend horizontally and vertically along the glass panel.
 4. The merchandiser of claim 2, wherein a portion of the serpentine conductive path has a zigzag profile adjacent a lower area of the glass panel.
 5. The merchandiser of claim 2, wherein the distance between two adjacent gaps located on a lower area of the glass panel is relatively narrow, and wherein the distance between two adjacent gaps located on an upper area of the glass panel is relatively wide.
 6. The merchandiser of claim 1, wherein the serpentine conductive path extends a distance that is greater than a length of the glass panel.
 7. The merchandiser of claim 1, wherein the glass panel assembly has an interior glass panel and an exterior glass panel, and the conductive coating is applied to one of the interior glass panel and the exterior glass panel.
 8. A door for a refrigerated merchandiser, the door comprising: a glass panel; a conductive coating applied to the glass panel and defining a serpentine conductive path on the glass panel.
 9. The merchandiser of claim 8, further comprising a plurality of gaps formed in the coating and defining the serpentine conductive path between adjacent gaps, and wherein a distance between adjacent gaps on the glass panel varies along the glass panel to vary the amount of heat applied to different areas of the glass panel.
 10. The merchandiser of claim 9, wherein the gaps extend horizontally and vertically along the glass panel.
 11. The merchandiser of claim 9, wherein a portion of the serpentine conductive path has a zigzag profile adjacent a lower area of the glass panel.
 12. The merchandiser of claim 9, wherein the distance between two adjacent gaps located on a lower area of the glass panel is relatively narrow, and wherein the distance between two adjacent gaps located on an upper area of the glass panel is relatively wide.
 13. The merchandiser of claim 8, wherein the serpentine conductive path extends a distance that is greater than a length of the glass panel.
 14. A door for a refrigerated merchandiser, the door comprising: a glass panel; a conductive coating applied to the glass panel and having a first gap defined in the coating along a periphery of the conductive coating, a second gap connected to and extending inward from the first gap disposed adjacent a first side of the glass panel toward a central area of the glass panel, and a third gap connected to and extending inward from the first gap disposed adjacent a second side of the glass panel toward a central area of the glass panel.
 15. The door of claim 14, wherein the second gap extends from the first side of the glass panel without intersecting the first gap disposed adjacent the second side of the glass panel.
 16. The door of claim 15, wherein the third gap extends from the second side of the glass panel without intersecting the first gap disposed adjacent the first side of the glass panel to direct a current in a zigzag profile along the glass panel.
 17. The door of claim 14, further comprising a plurality of second gaps and a plurality of third gaps.
 18. The door of claim 14, wherein at least one of the second gap and the third gap extends at a non-zero angle relative to a vertical axis and a horizontal axis.
 19. The door of claim 14, wherein at least one of the second gap and the third gap extends substantially horizontally across the glass panel.
 20. The door of claim 19, further comprising a fourth gap extending substantially vertically along the glass panel. 